Stock bottom end, stock 853 heads milled .035 w/ stock valves, MTI Stealth II cam......What will give me the tightest, yet safe quench?

 

I'd probably shoot for a .045" for a street setup.

 

I agree, but it depends on his piston/deck measurement.

 

The safest quench depends on who you ask. The street set-up is far easier on a motor and plenty run a .040. A race set-up is more extreme and guys like phil97svt run a .033 with no issues on a 100 runs plus a 100 shot. The generally accepted redline for thickness of quench is .020 but some feel .030 is the minumum. For the record I have 17k miles with no issues on a .027 gasket on my H/C/nos C5 with pistons .007 out of the hole. It is a forged 348. I may be the exception but .033 is fine and .04 for the street is safe.

If you asking for P/V distance you have to clay it.

 

Correct me if I'm wrong, the piston-to-deck (out-of-hole) is how much of the piston comes out of the cylinder into the heads at TDC?

 

.040 is the safe bet and will give you good compression. You do need to check the piston to valve clearance.

 

The piston never touches the head. It is the position of the piston relative to motor deck height (in the cylinder/flush/or out the cylinder.)
If you place the gasket over the heads, you'll see that the chamber area doesn't include all the circular area of the piston. There is a flat area. That flat area is the quench (or squish) are of the head. The only thing between that area and the piston is the gasket.
Now making that area tight improves flame travel and combustion, giving you a better burn during ignition of cylinder charge.
Stock castings have 1 quench area and some aftermarket castings like AFR have two, (part of the reason why they are so good).
Quench = Compressed gasket thickness - piston to deck height
This site has a pic that can help you understand (it is also a good SCR calc)
http://www.rbracing-rsr.com/compstaticcalc.html

I hope this helps